The purpose of this work is to obtain further understanding as to the chemical, physical and biological properties of insulin, the antidiabetogenic hormone. In some investigations, parts of the hormone will be removed, while in others, amino acid residues will be added to the hormone in studies on the relationship of structure to biological activity. Investigation will also be conducted on a practical synthesis of insulin from the A and B chains. BIBLIOGRAPHIC REFERENCES: Leucine Aminopeptidase (Bovine Lens): An Electron Microscopic Study. Allen Taylor and Frederick H. Carpenter (1977) Fed. Proc. 36, 809. Preliminary X-ray Study of Leucine Aminopeptidase (Bovine Lens), an Oligomeric Metalloenzyme. Francis Jurnak, Alexander Rich, Lucy van Loon-Klaassen, Hans Bloemendal, Allen Taylor and Frederick H. Carpenter (1977) J. Mol. Biol, in press.